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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1672
Experience:  GM Grand Master Technician 2007. 14 year experience.
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I have some questions expert, licenced mechanic who knows

Customer Question

I have some questions for an expert, licenced mechanic who knows the 1996 GMC 2500. The area of knowledge would be transmission and rear gears. Thanks, Steve.
Submitted: 1 year ago.
Category: GMC
Expert:  GM Bob replied 1 year ago.

Hello my name is ***** ***** I can help?

Customer: replied 1 year ago.
Hello Bob. I am calling from Calgary, Alberta. I was unavailable after 5pm yesterday but I am now back at my computer. It is almost 7am here so maybe we could continue with my discussion later this morning. I would much prefer that we talk on the phone. You can reply to me on this page or you can call me on the phone @(###) ###-####when your ready to continue...
Expert:  GM Bob replied 1 year ago.

Just to let you know a phone call is additional money.

Let me know what info you need, See if we can do it here.

Thank you

Customer: replied 1 year ago.
I have a 4L60-E tranny and the original 373 rear end in this truck. The vehicle is appraised at $19,000 and only has 178000km on the body. The motor is a 5.7 Vortec and has 275hp. I replaced it new from GMC and it only has about 40,000km on it. I have owned the truck for 4 years and I am the third owner. The rear gears are in rough shape due to the first owner towing a fifth wheel. The truck is only two wheel drive but is marked as a 2500 due to the upgrade factory suspension. My question is; The performance mechanic that I have for the last four years will install a new tru-track posi system next week. Due to the four speed transmission, what proper gear ratio should I be installing? We currently are ready to put in 373 but the RPM and chugging sound from the motor / exhaust at 70km an hour sounds like a 4 speed manual going to slow in fourth gear. What do you recommend ? I do not tow anything on a regular basis.
Expert:  GM Bob replied 1 year ago.

Need to do some research

Customer: replied 1 year ago.
Hi. So what do you recommend ? At the moment all the gearing except axles is included in my install.
Customer: replied 1 year ago.
Np, I wait for your response...
Customer: replied 1 year ago.
The cat's have been cut out and the new motor has been dyno'd against the transmission to bring the harmonic lines closer together on the chart. I will pay again to have ceramic headers installed and a deeper thrush style muffler added.
Expert:  GM Bob replied 1 year ago.

Sorry for the delay just got back home.

I would not think you would have to go to a 4.10 rear end.

When you say its chugging at 70km. Is the trans lockup converter engaged?

Do you have a programmer installed that lets you change shift points?

Customer: replied 1 year ago.
Hi. When you say "you do not think" I was kind of hoping that for sixty dollars you could give me a more informative response as I am already knowledgeable up to your answer level just as a layman already... I will ask my tech tomorrow and get back to your questions.
Expert:  GM Bob replied 1 year ago.

The problem of chugging is not the rear end. Unless you want more performance at the low end than you need to change to a 4.10 rear end.

The 3.73 most I would go.

I think your trans is up shifting to soon.

Customer: replied 1 year ago.
Hi. Thank you. I will get back to you tomorrow. By the way, where in our great country am I talking to ?
Expert:  GM Bob replied 1 year ago.

Indiana USA